Microstructure and electrochemical behavior of Fe-based amorphous metallic coatings fabricated by atmospheric plasma spraying

A Fe ₄₈Cr ₁₅Mo ₁₄C ₁₅B ₆Y ₂ alloy with high glass forming ability (GFA) was selected to prepare amorphous metallic coatings by atmospheric plasma spraying (APS). The as-deposited coatings present a dense layered structure and low porosity. Microstructural studies show that some nanocrystals and a fraction of yttrium oxides formed during spraying, which induced the amorphous fraction of the coatings decreasing to 69% compared with amorphous alloy ribbons of the same component. High thermal stability enables the amorphous coatings to work below 910 K without crystallization. The results of electrochemical measurement show that the coatings exhibit extremely wide passive region and relatively low passive current density in 3.5% NaCl and 1 mol/L HCl solutions, which illustrate their superior ability to resist localized corrosion. Moreover, the corrosion behavior of the amorphous coatings in 1 mol/L H ₂SO ₄ solution is similar to their performance under conditions containing chloride ions, which manifests their flexible and extensive ability to withstand aggressive environments.